Question

At the level of yeast cells, in a large population, selection favors?

1) a high proportion of parasitic mitochondria
2) a high proportion of non-parasitic, respiring mitochondria
3) equal proportions of parasitic and non-parasitic mitochondria
4) a loss of all non-parasitic mitochondria

Answer 1

Selection favors a high proportion of non-parasitic, respiring mitochondria in yeast cells.

Step-by-step explanation:

In a large population of yeast cells, selection favors a high proportion of non-parasitic, respiring mitochondria (option 2). Non-parasitic, respiring mitochondria are more advantageous in providing energy through respiration compared to parasitic mitochondria.

Yeast cells primarily reproduce asexually through budding, but they can also undergo sexual reproduction through meiosis. Sexual reproduction allows for genetic diversity and the potential removal of detrimental mutations from the population, which could be advantageous in the long term.

Fitness studies in yeast have shown that sexual reproduction can increase the frequency of beneficial mutations and help purge detrimental mutations. This suggests that selection would favor a high proportion of non-parasitic, respiring mitochondria as they contribute to the overall fitness of the yeast population.